510 
PROFESSOR J. J. THOMSON ON SOME APPLICATIONS OF 
K6 = 
ym 
P 
5 
where p is the pressure and p the density. 
Let H' be the amount of heat produced when c grammes of A combine, c being the 
combining weight of A, then 
H' = Nc 
dw 
5 
where N is the number of equivalents in a gramme of A. In order to simplify the 
reasoning, let us suppose that we are considering a case where the molecule and the 
equivalent are identical, 
1_ dw _ H / 
Iv0 dg N mpc 
P 
since 
IT 
~~ p c Ip 
N m = 1. 
Since pcjp is the same for all gases, and since for Hydrogen it is about 10 n /4 - 5, we 
have 
1 dw _4'5 H' 
V6d% = 10 11 
and therefore, by equation (62), 
Soy _ 4-5 H 7 S0 
co ~ ~ 10 n 0 ’ 
In the case of hydrochloric acid, sulphuric acid, sodium sulphate, and sodium 
chloride Thomsen # found H' = 2 X 10 s X 4'2 X 10 7 , so that in this case 
= 3 ~ approximately ; 
so that a temperature of about 30° C., an alteration of 1 C., would make a change of 
about 1 per cent, in the value of oj. 
§ 15. The formula 
rf'e s 
% p v q 
dw p 
_ Qr+s-p-s Q grfJKfl 
enables us to calculate readily the disturbing effect produced by any slight alteration 
in the external circumstances. 
* Lothar Meter: ‘Theorien der Cliemie,’ 4th edit., p. 4^8, 
